Library & files
Duplicate detection
Duplicate detection finds the same record stored more than once — usually by comparing artist and title after normalising punctuation and case, sometimes by duration or by an identifier inside the file.
Measured in our catalog
Matching on normalised artist and title, 357 groups in our catalog hold the same record twice — and dropping the version suffix finds 1,464 more.
The exact pass covers 729 of 443,460 tracks, and sampled, they are one record licensed to several labels and compilations — precisely what a DJ ends up with after buying from two stores. The version-blind pass covers 2,978, four times as many, and most of those are cuts you would keep both of. The gap between the two numbers is the whole problem: a looser matcher finds more and is right less often.
357
Exact duplicate groups
729
Tracks involved
1,464
Version-blind groups
2,978
Tracks involved
Measured on 11 August 2026 across public tracks grouped on normalised artist plus normalised title, then on normalised artist plus the title with its trailing version suffix removed.
Why it matters
Duplicates cost you more than disk space. Two copies of a record means two sets of cue points, two grids and a coin flip about which one your search returns, and the one you load is rarely the one you prepared.
The hard part is that a duplicate is a judgement, not a string comparison. The original and the extended mix are different records; the same record from two stores is not; and no automatic pass can tell you which of those you are looking at.
Frequently asked
How do you find duplicates in Rekordbox?+
Sort by title and read down, or use the duplicate view where your software offers one. Whatever finds them, the decision about which copy to keep is yours — the copy with your cue points on it, usually.
Is an extended mix a duplicate of the original?+
No. They are different records with different lengths and different mix points, and a matcher loose enough to call them the same will also merge things you needed to keep apart.
Why do I have the same track twice?+
Usually because it was licensed to more than one release — a label single and a compilation — so both are legitimately in the store. In our own catalog that pattern accounts for most of the exact matches.
Related terms
ID3 tags
ID3 tags are the metadata written inside an audio file — title, artist, album, genre, year, comment, and on DJ files often BPM and key. They travel with the file rather than with the software that read it.
Library database
Your DJ software keeps its own database of everything it knows about your collection — file locations, beatgrids, cue points, crates, play history. The audio files sit elsewhere on disk; the database is what turns them into a library.
Remix
A remix is a new production built from another artist’s parts — usually a different arrangement, often a different genre and tempo. The original vocal or hook survives; almost nothing else has to.
Extended mix
An extended mix is the DJ cut of a release — a longer intro and outro with more bars of beats at each end, so there is room to mix in and out. It is the version that belongs in a set.